21 research outputs found
Ενεργειακή αξιολόγηση και προτάσεις για βελτίωση της ενεργειακής απόδοσης κτιρίων: η περίπτωση του Γυμνασίου Κουνουπιδιανών
No full textΔιπλωματική Εργασία που υποβλήθηκε στη Σχολή Μηχανικών Παραγωγής & Διοίκησης του Πολυτεχνείου Κρήτης.Περίληψη: Στην σύγχρονη Ευρώπη, ένα από τα μεγαλύτερα ενεργειακά προβλήματα είναι αυτό της κτιριακής κατανάλωσης, η οποία αποτελεί το 40% της καναλισκόμενης ενέργειας στην Ε.Ε. των 25. Στην Ελλάδα, μία χώρα με ήπιες κλιματολογικές συνθήκες, σύμφωνα με στοιχεία της Παγκόσμιας Τράπεζας, έχει τριπλασιαστεί η κατά κεφαλήν εκπομπή CO2 (Διοξειδίου του Άνθρακα) τα τελευταία 40 χρόνια, σε αντίθεση με χώρες της Βόρειας Ευρώπης στις οποίες παρατηρούμε μείωση των εκπομπών περισσότερο από 50% στο ίδιο χρονικό διάστημα.
Καθίσταται φανερό πλέον, αφενός μεν ότι είναι επιτακτική η ανάγκη για άμεση μείωση των εκπομπών CO2 στην Ελλάδα, αφετέρου δε ότι η επίτευξη ενός τέτοιου στόχου δεν είναι ακατόρθωτη, καθότι έχει ήδη επιτευχθεί σε χώρες με πολύ μεγαλύτερες ενεργειακές ανάγκες στις κτιριακές τους εγκαταστάσεις. Με τη μείωση της καταναλισκόμενης ενέργειας θα πετύχουμε όχι μόνο τη μείωση των εκπομπών CO2 που θα έχει ως αποτέλεσμα ένα φιλικότερο στους ανθρώπους περιβάλλον αλλά και τη μείωση των εξόδων των καταναλωτών, καθώς η τιμή της ενέργειας αυξάνεται χρόνο με το χρόνο.
Στη διπλωματική αυτή μελέτη αυτή θα εξετάσουμε ένα κτίριο του τριτογενούς τομέα και συγκεκριμένα το Γυμνάσιο Κουνουπιδιανών, με σκοπό σε πρώτο στάδιο την ανάλυση και καταγραφή των ενεργειακών αναγκών του κτιρίου, σε δεύτερο στάδιο την παρουσίαση προτάσεων για την βελτίωση της ενεργειακής απόδοσης του κτιρίου και τελικά τη σύγκριση της ενεργειακής απόδοσης του κτιρίου μετά την εφαρμογή των προτάσεων, σε σχέση με την υπάρχουσα κατάστασή του. Η μελέτη θα γίνει με τη χρήση του διαπιστευμένου εμπορικού προγράμματος ηλεκτρονικού υπολογιστή ΤΕΕ-ΚΕΝΑΚ
Passiver Erddruck unter stoßartiger Belastung
No full textKnowing the passive earth resistance under shock-type loads is extremely important to assure that the ultimate and serviceability limit states are not exceeded in the case of accidental actions due to collision of vehicles with structures. Previous papers that provide a calculation model validated by tests are not known. The research started with the static passive earth resistance mobilization in order to develop and validate a mathematical model, which was later extended for the dynamic case, by adding the inertial forces. The model was transposed in a calculation program and was validated on small scale physical models.
The applicability of the model can be extended to any type of vertical plane structures, which are in contact with the retained soil, and for which a horizontal displacement is expected, and which can be assimilated by a plane strain state. As an alternative, the physical tests were also analyzed by the finite element method, using the PLAXIS 2D software. The results obtained for the dynamic case offer a safe approximation and they are presented within the paper.
Finally, several selected practical examples of applying the mathematical model developed by the author are presented. The examples consist of passive earth pressure calculations, in case several common transportation vehicles collide with retaining walls. Furthermore, a simplified preliminary analysis is recommended as exemplified in chapter 6.8, in order to identify the design cases in which the dynamic response may lead to the system’s loss of stability.
As a main result of the research, for practical cases the design engineer may use the values of the ultimate static passive displacement and resistance given by any standard, literature reference or model as input in the mathematical model developed by the author in order to calculate the horizontal parallel displacement of a planar full-scale structure subjected to any shock-type load. For a simplified preliminary approach, the use of the charts represented in the figures 6-24 and 6-25 is recommended. For more complex cases or need for accurate results in special cases, further research is required as outlined in the proposed development possibilities.Die Kenntnis des passiven Erddruckes unter Stoßbelastungen ist äußerst wichtig, um sicherzustellen, dass die Grenzzustände der Standsicherheit und Gebrauchstauglichkeit bei außergewöhnlichen Einwirkungen aufgrund einer Kollision von Fahrzeugen mit Bauwerken nicht überschritten werden. Frühere Arbeiten, die ein durch Versuche validiertes Berechnungsmodell bereitstellen, sind dem Autor nicht bekannt.
Die Forschung begann mit der statischen Mobilisierung des passiven Erdwiderstands, um ein mathematisches Modell zu entwickeln und zu validieren, das später für den dynamischen Fall durch Hinzufügen der Trägheitskräfte erweitert wurde. Das Modell wurde in ein Berechnungsprogramm umgesetzt und anhand von kleinen Modellversuchen validiert. Die Anwendbarkeit des Modells kann auf jede Art von vertikalen ebenen Tragwerken ausgedehnt werden, die mit dem gestützten Boden in Kontakt stehen und für die eine horizontale Verschiebung erwartet wird und die durch einen ebenen Verformungszustand assimiliert werden können. Alternativ wurden die physikalischen Tests auch mit der Finite-Elemente-Methode unter Verwendung der PLAXIS 2D-Software analysiert. Die für den dynamischen Fall erhaltenen Ergebnisse bieten eine sichere Annäherung und werden in der Arbeit dargestellt.
Abschließend werden einige ausgewählte praktische Beispiele für die Anwendung des vom Autor entwickelten mathematischen Modells dargestellt. Die Beispiele bestehen aus passiven Erddruckberechnungen für den Fall, dass mehrere gängige Transportfahrzeuge mit Stützmauern kollidieren.
Darüber hinaus wird eine vereinfachte Analyse empfohlen, wie im Kapitel 6.8 veranschaulicht, um die Entwurfsfälle zu identifizieren, in denen das dynamische Verhalten zum Verlust der Standsicherheit des Systems führen kann. Als Hauptergebnis der Forschung kann der Planungsingenieur für praktische Fälle die Werte der statischen passiven Grenzverschiebung und des Erdwiderstands verwenden, die in Normen, Regelwerken, Literatur oder einem Modell als Eingabe in das vom Autor entwickelte mathematische Modell angegeben werden, um die horizontale parallele Verschiebung eines ebenen Tragwerks zu berechnen, die einer Stoßbelastung ausgesetzt ist. Für einen vereinfachten praktischen Ansatz wird die Verwendung der in den Abbildungen 6-24 und 6-25 dargestellten Diagramme empfohlen. Für komplexere Fälle oder die Notwendigkeit genauer Ergebnisse in besonderen Fällen sind weitere Untersuchungen erforderlich, wie in den vorgeschlagenen Entwicklungsmöglichkeiten dargelegt
Circulating endothelial progenitor cells in periodontitis.
No full textBACKGROUND
Several biologically plausible mechanisms have been proposed to mediate the association between periodontitis and atherosclerotic vascular disease (AVD), including adverse effects on vascular endothelial function. Circulating endothelial progenitor cells (cEPCs) are known to contribute to vascular repair, but limited data are available regarding the relationship between cEPC levels and periodontitis. The aims of this cross-sectional study are to investigate the levels of hemangioblastic and monocytic cEPCs in patients with periodontitis and periodontally healthy controls and to associate cEPC levels with the extent and severity of periodontitis.
METHODS
A total of 112 individuals (56 patients with periodontitis and 56 periodontally healthy controls, aged 26 to 65 years; mean age: 43 years) were enrolled. All participants underwent a full-mouth periodontal examination and provided a blood sample. Hemangioblastic cEPCs were assessed using flow cytometry, and monocytic cEPCs were identified using immunohistochemistry in cultured peripheral blood mononuclear cells. cEPC levels were analyzed in the entire sample, as well as in a subset of 50 pairs of patients with periodontitis/periodontally healthy controls, matched with respect to age, sex, and menstrual cycle.
RESULTS
Levels of hemangioblastic cEPCs were approximately 2.3-fold higher in patients with periodontitis than periodontally healthy controls, after adjustments for age, sex, physical activity, systolic blood pressure, and body mass index (P = 0.001). A non-significant trend for higher levels of monocytic cEPCs in periodontitis was also observed. The levels of hemangioblastic cEPCs were positively associated with the extent of bleeding on probing, probing depth, and clinical attachment loss. Hemangioblastic and monocytic cEPC levels were not correlated (Spearman correlation coefficient 0.03, P = 0.77), suggesting that they represent independent populations of progenitor cells.
CONCLUSION
These findings further support the notion that oral infections have extraoral effects and document that periodontitis is associated with a mobilization of EPCs from the bone marrow, apparently in response to systemic inflammation and endothelial injury
A Scalable and Semantic Data as a Service Marketplace for Enhancing Cloud-Based Applications
No full textData handling and provisioning play a dominant role in the structure of modern cloud–fog-based architectures. Without a strict, fast, and deterministic method of exchanging data we cannot be sure about the performance and efficiency of transactions and applications. In the present work we propose an architecture for a Data as a Service (DaaS) Marketplace, hosted exclusively in a cloud environment. The architecture includes a storage management engine that ensures the Quality of Service (QoS) requirements, a monitoring component that enables real time decisions about the resources used, and a resolution engine that provides semantic data discovery and ranking based on user queries. We show that the proposed system outperforms the classic ElasticSearch queries in data discovery use cases, providing more accurate results. Furthermore, the semantic enhancement of the process adds extra results which extend the user query with a more abstract definition to each notion. Finally, we show that the real-time scaling, provided by the data storage manager component, limits QoS requirements by decreasing the latency of the read and write data requests
Factors that determine the unusually low reduction potential of cytochrome c550 in cyanobacterial photosystem II
No full textA study of a protein that shuttles electrons during plant photosynthesis. The electrons are eventually taken away from water and in the process, oxygen is produced. --author-supplied descriptio
High-frequency EPR study of a new mononuclear manganese(III) complex: [(terpy)Mn(N3)3] (terpy = 2,2\u27:6\u27,2\u27\u27-Terpyridine)
No full textA study of another mimic of the enzyme that is responsible for the evolution of oxygen gas during photosynthesis. This paper concentrates on the structure of the molecule. --author-supplied descriptio
Dimensions of informal care in Greece: the family's contribution to the care of patients hospitalized in an oncology hospital
No full textAims and objectives. This study aims to explore the kind and frequency of care provided to hospitalized cancer patients by relatives and the reasons for providing this care.
Background. Informal care is a common phenomenon across many countries. In Greece, informal caring activities occur in most hospitals. Patients' relatives stay by their bedside for long hours and assist with care. This phenomenon is highly correlated with the nursing staff shortage.
Method. This study was carried out in a Greek oncology hospital. The sample consisted of 150 informal caregivers. We used a 37-item questionnaire called In-Hospital Informal Care Questionnaire Acute Care.
Results. The participants provide substantial help to their patients daily. On average, they stay by their bedside for 20·23 hours in a 24-hour period. Additionally, 104 participants stated that they hire a privately paid patient's helper.
The relatives stay by their patients' bedside for various reasons such as: (1) severity of the condition; (2) providing psychological support; (3) family tradition; (4) because they do not believe their patients are safe in the hospital without their supervision; or (5) the nursing staff shortage.
Conclusions. The participants offer informal care that reflects specific nursing duties. We could argue that Greek hospitals 'use' relatives as unpaid labour to compensate for the nursing shortage. It is disquieting that usually someone from the hospital staff suggests to the relatives to stay at the patient's bedside even after visiting hours or to hire a private paid patient's helper. This implies that the staff considers such contribution necessary.
Relevance to clinical practice. The findings show that relatives perform daily tasks that nurses should be performing. They indicate that the hospital should introduce specific staffing policies for reducing families' burden. Our findings could influence future staffing plans of nursing managers, policy makers or health authorities
Thermomechanical Properties of Carbon Nanocomposites PEGDA Photopolymers
No full textIn this work, UV-curable resin poly (ethylene glycol) diacrylate (PEGDA) was reinforced with three different types of nanofillers: pristine graphene (G), multiwalled carbon nanotubes (MWNTs), and a hybrid of MWNTs and graphene 70/30 in mass ratio (Hyb). PEGDA was mixed homogenously with the nanofiller oligomer by shear mixing and then photopolymerized, affording thin, stable films. The thermomechanical properties of the afforded nanocomposites indicated the superior reinforcing ability of pristine graphene compared with MWNTs and an intermediate behavior of the hybrid
Characterization of the O2-Evolving reaction catalyzed by [(terpy)(H2O)MnIII(O)2MnIV(OH2)(terpy)](NO3)3 (terpy = 2,2\u27:6,2\u27\u27-Terpyridine)
No full textA study of a mimic of the enzyme that is responsible for the evolution of oxygen gas during photosynthesis. The mimic does indeed make oxygen from water and in this paper we describe the details of the reaction through a variety of means. (author-supplied description
